The ABCDE dermoscopy algorithm for early detection of melanoma. Which additional letter (F) was added to address a common melanoma variant that lacks all ABCDE features?

• A F = Familial melanoma genes (CDKN2A, CDK4)
• B F = Frequency of sun exposure history
• C F = Features of dermoscopy (atypical network, regression structures)
• D F = Funny-looking lesion (ugly duckling sign) ✓

Explanation

The 'ugly duckling sign' (sometimes listed as 'F') captures nodular and amelanotic melanomas that lack classic ABCDE features — they stand out as lesions that look different from all other nevi on a patient ('funny-looking'). These are the dangerous melanomas missed by ABCDE criteria. A solitary lesion unlike the patient's other moles should prompt biopsy even without asymmetry, border irregularity, colour variation, diameter >6mm, or evolution.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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